Not a hardware/chip person here, so I found this text helpful regarding memory tagging: "As one might expect, the Arm64 architecture uses 64-bit pointers to ad

Not a hardware/chip person here, so I found this text helpful regarding memory tagging: "As one might expect, the Arm64 architecture uses 64-bit pointers to address memory. There is no need (yet!) for an address space that large, though, so normally only 48 of those bits are actually used by the hardware." ... "MTE allows the storage of a four-bit "key" in bits 59-56 of a virtual address — the lower "nibble" of the top byte. It is also possible to associate a specific key value with one or more 16-byte ranges of memory. When a pointer is dereferenced, the key stored in the pointer itself is compared to that associated with the memory the pointer references; if the two do not match, a trap may be raised." From this article at the ever-wonderful lwn.net: https://lwn.net/Articles/834289/ https://lwn.net/Articles/834289/